Conventionally, there has been known a thermal printer including a thermal head, a platen, a sheet cutter provided on the downstream side of the thermal head, a reflective optical sensor provided at a position facing the tip end of the sheet cutter, and a warning buzzer. At the time of starting printing, the thermal printer reverses the platen to perform back feed by a prescribed amount so that the tip end of a print sheet comes to a printing position. If the print sheet is not detected by the reflective optical sensor before performing the back feed, the thermal printer rings the warning buzzer. In the way described above, the thermal printer prevents idle printing (see Patent Document 1).
[Patent Document 1] JP-U-63-106646